Transparent Polyimide Substrate for Flexible TFT Fabrication
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Solution Overview
Problem
Conventional polyimide substrates used in flexible displays are not transparent and lack high thermal resistance, making them unsuitable for high-temperature TFT processes in flexible flat panel display fabrication.
Innovation Solution
A soluble polyimide polymer with a polycyclic aliphatic group, aromatic group containing ether bonds, and specific diamine and dianhydride ratios is developed, providing high thermal resistance, chemical resistance, and transparency, suitable for flexible flat panel display fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polyimide substrate is used, then thermal resistance is achieved, but transparency is lost (substrate becomes yellow)
Solution Approach 1:
The patent modifies the chemical structure parameters of polyimide by incorporating specific aromatic diamine components with ether bonds and controlling the ratio of different monomers (1≦n/m≦4) to achieve both high thermal resistance (Tg>300°C) and transparency, eliminating the yellowing problem of conventional polyimide
Solution Approach 2:
The patent creates a composite polyimide structure by copolymerizing multiple components including aromatic diamine with ether bonds, polycyclic aliphatic group-containing dianhydride, and other diamines, achieving synergistic effects that provide both thermal stability and optical clarity
2Stability of the object's composition
If flexible plastic film material is used, then flexibility is achieved, but chemical resistance and dimensional stability at high temperature are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters by introducing aromatic groups with ether bonds and polycyclic aliphatic structures, which provide high glass transition temperature and resistance to chemical erosion from etching and development processes while maintaining flexibility
Solution Approach 2:
The patent introduces specific functional groups (ether bonds, aromatic rings, polycyclic structures) at strategic positions in the polymer chain to provide localized resistance to chemical attacks during TFT processes while maintaining overall flexibility and dimensional stability
3Reliability
If polyimide substrate endures high-temperature TFT processes, then processing capability is improved, but transparency deteriorates
Solution Approach 1:
The patent optimizes the chemical structure parameters by selecting specific monomer ratios and incorporating transparent aromatic structures that maintain optical clarity even after exposure to high-temperature TFT processes (>200°C), ensuring both process reliability and visual quality
Data Source
AI summary
A method for fabricating a flexible electrical device is provided. The method includes providing a first substrate, providing a second substrate opposed to the first substrate, wherein one of the first and second substrates includes a polyimide polymer of Formula (I)wherein B is a polycyclic aliphatic group, A is an aromatic group containing at least one ether bond, A′ is an aromatic or aliphatic group, and 1≦n/m≦4, directly fabricating a thin film transistor (TFT) on one of the first and second substrates which includes the polyimide polymer of Formula (I), and disposing a medium layer between the first substrate and the second substrate.